Self-drilling anchor bolt assembly



y 8, 1968 c. D. POLOS 3,385,156

SELF-DRILLING ANCHOR BOLT ASSEMBLY Filed March 30, 1966 2 Sheets-Sheet lWWII" May 28, 1968 c. D. POLOS 3,385,156

SELF-DRILLING ANCHOR BOLT ASSEMBLY Filed March 30, 1966 2 Sheets-Sheet?6 4/ 43 YIIIIIII I-- III/M 44 INVENTOR CdvzaZmzizkeefl oa )zyW, 4

A T TORNEYS United States Patent 3,385,156 SELF-DRILLING ANCHOR BOLTASSEMBLY Constantine D. Polos, Park Ridge, 111., assignor to Dan PolosIndustries, Inc, Addison, 111., a corporation of Illinois Filed Mar. 30,1966, Ser. No. 538,778 6 Claims. (C1. 85-68) ABSTRACT OF THE DISCLOSUREA self-drilling anchor bolt assembly provided with integral rotary meansfor drilling the hole in which the assembly is placed for use.

This invention relates to bolt anchors used to attach bolts to walls,floors, and the like, and, more particularly, it relates to anchors ofthe type having an intermediate collapsible section which expandstransversely into contact with the inner surface of a wall in which theanchor is installed.

Anchor bolts of the general type with which this invention is concernedhave long been known to the art. An anchor bolt of this type comprisesan elongated hollow body having an intermediate portion which collapseslongitudinally and expands outwardly to engage the inner surface of awall, when the associated bolt is rotated to bring about collapse of thesleeve. In use, such anchors require the drilling of a hole of suitablesize in the wall, into which the anchor is placed. A disadvantage ofthis type of anchor is the fact that a drill must be available formaking the hole into which the anchor is placed. Since the size of thehole must be correlated with the size of the anchor, it is required thatthe user of such anchors have available a supply of dillerent sizeddrill bits for use whenever an anchor is to be installed.

Several attempts to eliminate the necessity for having and using aseparate drill have been made, as evidenced by prior patents describinganchors provided with means for forming their own holes. In general,these means comprise sharpened points on the ends of the anchors whichpermit the anchors to be driven in the manner of nails. Although suchconstructions may be suitable in small sizes and when used in relativelysoft materials, they cannot be used effectively in the larger sizes norcan they be used with hard wall surfaces, such as those made of plywood.

The anchor of the present invention obviates the necessity for use of aseparate drill by being provided on its end with a cutting head thatcuts a hole through the wall of a size commensurate with the size of theanchor itself, being thereby much more convenient in use. In anotheraspect, the invention is provided with means which indicates when theintermediate collapsible portion of the sleeve has been suflicientlycollapsed to make secure contact with the inner surface of the wall andwhich further improves the gripping action against such surface.

The invention will be better understood from the following detaileddescription thereof, taken in conjunction with the accompanyingdrawings, in which:

FIGURE 1 is a side view of a typical anchor bolt assembly of theinvention in its normal or uncollapsed condition;

FIGURE 2 is a view of the assembly of FIGURE 1 after it has beeninstalled, showing the gripping action against the wall of lugs attachedto the collapsed middle portion of the sleeve;

FIGURE 3 is a right-hand view of the assembly of FIGURE 1 showing thecutting head and the staggered wall retaining tangs in the head flange;

FIGURE 4 is a cross-sectional view through the cutting head, along theline 4-4 of FIGURE 2;

FIGURE 5 is a fragmentary view in partial section of another embodimentof the invention showing a different type cutting head and of the meansof securing threaded engagement between the bolt and the sleeve;

FIGURE 6 is a cross-sectional view along the line 66 of FIGURE 5 showingthe inwardly projecting ears used to engage the threads of the bolt;

FIGURE 7 is a view of another embodiment having a cutting head similarto that of FIGURE 5 in which a ditferent means for forming the threadedengagement between the cutting head and the bolt is used;

FIGURE 8 is a cross-sectional view along the line 88 of FIGURE 7;

FIGURE 9 is a left-side view of the bolt of FIG- URES l and 2 showingthe socket means for rotation of the bolt;

FIGURE 10 is a side view of the bolt head of FIG- URE 9 in partialsection showing the socket used for rotating the bolt; and

FIGURE 11 is a fragmentary view of a cutter head similar to that shownin FIGURES l and 2 in which the lugs for threaded engagement with thebolt are formed by triangular coupons punched in the wall of the sleeve.

Referring to FIGURES l and 2, the anchor assembly of the inventionconsists of two separable pieces which are threadedly engaged. The firstof these, bolt 10, is received within the second, an elongated,generally tubular body portion 11 which in turn consists of a sleeve 12and a cutting bead 13 interconnected by a plurality of connecting strips14. The end of the body 11 away from the cutting head is provided with ahead flange 16 equipped with a plurality of tangs 17 which engage thewall 15 in which the anchor is used in order to prevent rotation of theanchor. Bolt 10, which is received by body portion 11, is provided witha threaded shank 18 terminating in a sharpened point 19 which acts as apilot for cutting head 13 when the anchor is used. Although squarethreads are shown in the embodiment of FIGURES 1 and 2, any other threadshape could also be used, as will be apparent to those skilled in theart. Cutting head 13 is internally threaded to match the threads onshank 18 by means of which longitudinal movement of cutting head 13toward bolt head 20 can be obtained on rotation of the bolt.

In the embodiment of the cutting head shown in FIG- URES 13, cuttinghead 13 is provided with cutting lips 21 which function in a mannersimilar to that of a conventional twist drill on rotation of the bodyportion 11. In the uncollapsed form of the anchor assembly, shown inFIGURE 1, the sharpened point 19 of bolt 10 extends sufficiently beyondthe end of cutting head 13 to act as a pilot for the hole to be drilled.

Interconnecting strips 14 are weakened at predetermined pointsintermediate their ends, at which weakened points the strip will bendoutwardly, i.e., transversely of the anchor axis, when a compressiveforce is applied to the ends thereof. In the embodiment shown in FIG-URES 1 and 2, the weakened point is established at 22 by a decrease inthe width of the strip at this point and by the inclusion of a diegroove 24 which insures that the strip will bend at the desired point,thereby dividing the length of the strip into two unequal portions, ashorter portion 23 connected to sleeve 12 and a longer portion 25connected to cutting head 13.

In a preferred embodiment of the invention, as shown in FIGURES 1 and 2,strips 14 are provided with lugs 26 at the weakened point 22. Lugs 26are generally triangular in shape and are inwardly depressed in theuncollapsed form of the anchor shown in FIGURE 1.

When connecting strips 14 are collapsed, by movement of cutting head 13toward sleeve 12, as shown in FIGURE 2, lugs 26 assume a positiongenerally perpendicular to the inner surface of wall 15. This collapsingmovement is brought about by rotation of bolt 10 while holding bodyportion 11 stationary. As strips 14 collapse, lugs 26 ap proach and areeventually embedded into the wall. Lugs 26 thereby serve two functions:firstly, the increase in resistance by turning of bolt 10, which is feltwhen the lugs 25 contact wall 15, serves as an indication that collapseof strips 14 has progressed far enough and thereby avoids overtighteningwhich may result in loosening of the anchor within the wall withconventional constructions of the type heretofore known; secondly, theengagement of lugs 26 with wall 15 aids in preventing undesired rotationof body portion 11 when bolt 10 is rotated to be removed and replaced inthe installed anchor.

As a further protection against rotation of the body portion 11 whilestrips 14 are being collapsed in order to fix the anchor, head flange 16is provided with a plurality of inwardly directed tangs 17, as shownparticularly in FIGURE 3. In order to increase the holding power of thetangs, the faces thereof are inclined radially at different angles,e.g., a and ,8, as shown, thus positioning the pointed ends thereof atdifferent distances from the longitudinal axis of body portion 11. Inthis manner, the resistance to rotation is considerably enhanced overthat which would have been obtained had the points all fallen at thesame distance from the axis.

The cutting head shown in FIGURES 1 and 2 is obtained by pinching theend of body portion 11 to obtain two laterally extending protuberancesor ears 31 diagonally disposed on the end of body portion 11, as shownin FIGURE 4. Each of cars 31 is ground in a plane oblique to the axis ofbody portion 11 to obtain a cutting lip 21 of the conventional typefound on a twist drill. It should be observed that cars 31 must be wideenough so that the hole drilled by rotation of the anchor assembly hassufi'icient diameter to clear both sleeve 12 and the interconnectingstrips 14 which are advisably outwardly slightly bowed in theuncollapsed form of the device in order to insure that the stripscollapse outwardly as desired when collapsing force is applied.

The embodiment shown in FIGURES 1-3 is internally threaded withincutting head 13 by means of a conventional tapping operation.Alternative methods of obtaining threaded engagement between the boltand the cutting head are shown in FIGURES 5 and 7. In both of theseembodiments, inwardly directed ears 41 (FIGURES 5 and 6) and 51 (FIGURES7 and 8) are obtained by shearing coupons of metal from the tubular wallportion of the cutting heads. In FIGURES 5 and 6, the inwardly directedcoupons are sheared on two opposing sides and bent on the remaining twosides so as to produce inwardly extending ears 41 which are positionedto engage the threads of bolt 42. In FIGURES 7 and 8, ears 51 areproduced by shearing a coupon on three sides and bending it on theremaining side, again to produce inwardly directed projections whichengage the threads of bolt 52.

Still another form of threaded engagement which can be used in thecutting head is depicted in FIGURE 11 which shows a two-bladed cuttinghead 61 similar to that shown in FIGURES l and 2 provided with aplurality of triangular partially cut-out coupons 62 which extendradially inwardly to engage the triangular threads of a bolt intended tobe used therewith.

The cutting heads shown in FIGURES 5 and 7 are of a type which differsfrom that of FIGURES 1 and 2 and represents an alternative construction.The heads 43 and 53 contain saw teeth 44 and 54, such as thoseconventionally found in a circular saw, which may be alternatelystaggered to provide clearance for the chips which are formed. In anyevent, however, the hole which is drilled must have sufiicient diameterto clear the widest portion of the anchor which is inserted therein,

The embodiment of FIGURE 7 also illustrates an alternative form ofconstruction for connecting strips 54 which are not provided withwall-engaging lugs as are those illustrated in FIGURES 1 and 2. Inaddition, strips 54 are stiffened at their bending points 55 by beingcrowned instead of having a die groove.

In order to drill the initial hole with the anchor of the invention, thebolt, e.g., 10, is first screwed as far as it will go into firmengagement with head flange 16 (FIGURE 1). At this point, furtherrotation of the bolt will cause rotation of the cutting head 13. Thepilot point 19 is placed in a desired location on the wall, and theentire assembly is rotated, preferably with a power drill butalternatively by a hand drill, thereby causing the cutting head 13 todrill a hole into the wall. In order to avoid drilling too far andthereby causing tangs 17 to score the outer surface of the wall 15,sleeve 12 is provided with an easily visible circumferential band anddot 27 of a suitable contrasting color which, when seen to be flush withthe outer surface of the wall, indicates imminent engagement of thetangs with the wall surface and serves as an indication that furtherdrilling should be stopped.

FIGURES 9 and 10 show the details of a desirable configuration of thebolt head 20 (FIGURE 1) for use in the invention. The head 20 isprovided with a socket 28, suitably hexagonal, as well as a transverseslot 29, which permits either the use of a mating hexagonal wrench or aconventional or special screw driver (i.e., one equipped, if desired,with a central positioning lug) for use in drilling the hole in the wallin which the anchor is to be used and for rotating the bolt to cause theanchor to collapse into firm engagement therewith.

After a hole has been drilled in the wall, as described above, headfiange 16 is then driven into the wall by means of suitable pressure,thereby immobolizing body portion 11. By then rotating bolt 10, cuttinghead 13 will be drawn toward the wall 15 causing collapse of theconnecting strips 14 in the manner previously described.

It will be seen that the construction of the invention eliminates thenecessity for a separate drill for use with the anchor, which drill maybe unavailable when use of the anchor is desired. The locking lugs,which are provided intermediate the ends of the collapsible strip,further contribute to the effectiveness of the device by preventinginadvertent overtightening as well as providing for secure engagement ofthe anchor with the inner surface of the wall on which it is used.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, as modifications will be obvious to those skilled in the art.

What is claimed is: I

1. A self-drilling bolt anchor assembly comprising:

a bolt having a threaded shank, an enlarged head on one end of the shankprovided with means for rotating said shank, and a sharpened point onthe other end thereof;

a sleeve encircling said bolt adapted to project through an opening in awall;

an annular flange attached to the outer end of said sleeve;

tang means carried by said flange for preventing rotation of said sleevewhen said flange is in contact with said Wall;

an internally threaded rotary cutting head removably engaging said shankand spaced from said sleeve, said head including cutting means;

a plurality of deformable connecting strips interconnecting said cuttinghead and said sleeve, each said connecting strip being weakened at apredetermined point so that it will collapse and bulge outwardly when alongitudinal compressive force is applied to the ends thereof, saidweakened point being spaced so as to divide said connecting strip into ashorter sleeve portion and a longer head portion.

2. The assembly of claim 1 in which said interconnectin strips areprovided with lugs at said weakened points which, on collapse of saidintermediate strips, engage said wall and serve to inhibit rotation ofsaid anchor.

3. The anchor of claim 1 in which said cutting means comprises a pair ofdiagonally opposed laterally extending pinched protuberances formed fromthe wall of said cutting head, each protuberance being provided On itsforward end with a cutting edge.

4. The anchor of claim 1 in which said cutting head means comprises aplurality of saw teeth circumferentially arranged on said cutting head.

5. The anchor of claim 1 in which the threaded engagement between saidcutting head and said threaded bolt is obtained by means of inwardlydirected coupons partially cut from the wall of said cutting head.

6. The anchor of claim 1 in which said tang means comprises a pluralityof generally triangular tangs partially cut from said rim and inwardlybent, the faces of said tangs being inclined radially at difierentangles, whereby said tan-gs are positioned at different radial distancesfrom the axis of said sleeve.

References Cited UNITED STATES PATENTS 422,307 2/1890 Libbey 85451,996,121 4/ 1935 Phillips 85-68 2,018,251 10/1935 Croessant 85712,707,012 4/1955 Cox 151--35 2,913,953 11/1959 Tendler 8571 FOREIGNPATENTS 408,668 4/ 1934 Great Britain.

EDWARD C. ALLEN, Primary Examiner.

